重點(diǎn)講解：
1. perch on
棲息；
eg. The bird took its perch on a tree branch.
鳥兒棲息在樹枝上。
eg. An eagle found a perch on the rock.
一只老鷹在巖石高處落腳。
eg. Gilded parrots perch on candleholders, their tiny tilted heads reflected in mirrors.
鍍金的鸚鵡棲息在燭臺(tái)上，它們斜側(cè)著的小腦袋映照在鏡中。
2. go back
追溯到；回溯到；
eg. Our association with him goes back four years.
我們同他的合作是從4年前開始的。
eg. We must go back to the Middle Ages to discover the origins of English plays.
我們必須追溯到中世紀(jì)才能找到英國(guó)戲劇的起源。
eg. To trace the origins of the Irish problem, we have to go back over three hundred years.
要探討愛(ài)爾蘭問(wèn)題的起因就要追溯到三百多年以前。